Mobile communication device and method for allocating resources outside of a virtual carrier based on UE capabilities

ABSTRACT

A communications device configured to receive data from a mobile communications network including one or more network elements providing a wireless access interface. The wireless access interface provides plural communications resource elements across a host frequency bandwidth, and includes, within the host frequency bandwidth, first communications resource elements within a first frequency bandwidth for allocation preferably to reduced capability devices to receive signals representing data transmitted by a transmitter within the first bandwidth forming a first virtual carrier, the reduced capability devices each having a receiver bandwidth greater than or equal to the first frequency bandwidth but less than the host frequency bandwidth. Communications devices of different capabilities can be allocated communications resources within different frequency ranges according to their capability, to relieve congestion on a center frequency of communications resources in which communications devices with a minimum bandwidth capability must receive communications resources for receiving down link signals.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based on PCT application PCT/GB/2014/050143filed Jan. 17, 2014, and claims priority to British Patent Application1301289.3, filed in the UK IPO on Jan. 24, 2013, the entire contents ofeach of which being incorporated herein by reference.

TECHNICAL FIELD OF THE DISCLOSURE

The present disclosure relates to communications devices, and methods ofcommunicating using mobile communications devices, infrastructureequipment for mobile communications networks, mobile communicationsnetworks and systems and methods of communicating using mobilecommunications networks.

BACKGROUND OF THE DISCLOSURE

Mobile communications systems continue to be developed to providewireless communications services to a greater variety of electronicdevices. In more recent years, third and fourth generation mobiletelecommunication systems, such as those based on the 3GPP defined UMTSand Long Term Evolution (LTE) architectures have been developed tosupport more sophisticated communications services to personal computingand communications devices than simple voice and messaging servicesoffered by previous generations of mobile telecommunication systems. Forexample, with the improved radio interface and enhanced data ratesprovided by LTE systems, a user may enjoy high data rate applicationssuch as mobile video streaming and mobile video conferencing that wouldpreviously only have been available via a fixed line data connection.The demand to deploy third and fourth generation networks is thereforestrong and the coverage area of these networks, i.e. geographiclocations where access to the networks is possible, is expected toincrease rapidly.

More recently it has been recognised that rather than providing highdata rate communications services to certain types of electronicsdevices, it is also desirable to provide communications services toelectronics devices that are simpler and less sophisticated. Forexample, so-called machine type communication (MTC) applications may besemi-autonomous or autonomous wireless communication devices which maycommunicate small amounts of data on a relatively infrequent basis. Someexamples include so-called smart meters which, for example, are locatedin a customer's house and periodically transmit information back to acentral MTC server data relating to the customer's consumption of autility such as gas, water, electricity and so on.

Whilst it can be convenient for a communications device such as an MTCtype device to take advantage of the wide coverage area provided by athird or fourth generation mobile telecommunication network there are atpresent disadvantages. Unlike a conventional third or fourth generationcommunications device such as a smartphone, an MTC-type device ispreferably relatively simple and inexpensive. The type of functionsperformed by the MTC-type device (e.g. collecting and reporting backdata) do not require particularly complex processing to perform.

As will be appreciated, there may be a desire for many types ofcommunications devices to conserve power. However this may beparticularly applicable to MTC type devices, which are arranged tooperate with a less sophisticated transceiver and may for example be lowpower and battery operated and for example may be deployed for asignificant time before the batteries are to be replaced. Accordinglythere is a desire to provide arrangements in which a power of all typesof communications devices operating with a mobile communicationsnetworks can be conserved.

SUMMARY OF THE DISCLOSURE

Embodiments of the present disclosure can provide in one example acommunication device for transmitting data to and receiving data from amobile communications network. The mobile communications networkincludes one or more network elements providing a wireless accessinterface for the communications devices. The wireless access interfaceprovides a plurality of communications resource elements across a hostfrequency range which is for example a full or host bandwidth availablefor the mobile devices to communicate via the mobile communicationsnetwork. A full bandwidth may correspond to the uplink or the downlinkof the mobile communications network. The mobile communications networkis adapted to provide a wireless access interface to include within thehost frequency bandwidth a first section of communications resourceelements within a first frequency bandwidth for allocation preferably toreduced capability devices forming a first virtual carrier. The reducedcapability devices each have a receiver bandwidth which is greater thanor equal to the first frequency bandwidth but less than the hostfrequency bandwidth. The mobile communications network preferablyallocates the communications resources to the reduced capability devicesin the sense that the reduced capability devices are given priority tothe communications resources of the first section of communicationsresources over the allocation of the communications resources tocommunications devices which are able to communicate using the fullbandwidth of the host carrier of the mobile communications network. Inone example, the first section of the communications resources formingthe first virtual carrier is reserved for allocation to the reducedcapability devices only, but in other examples, some of thecommunications resources of the first section of the first virtualcarrier may be allocated to the full capability communications devices,if a demand for the communications resources from the reduced capabilitydevices leaves some of the communications resources un-allocated.

A communications device is configured to transmit to the mobilecommunications network a relative capability of the communicationsdevice to transmit or receive the data via the wireless accessinterface, the relative capability comprising at least an indication ofa relative bandwidth of the receiver to receive signals within the hostfrequency range greater than or equal to the first bandwidth. The mobilecommunications device is configured to receive an allocation ofcommunications resources outside the the first virtual carrier inresponse to the indication of the relative capability of the deviceindicating that the communications device can receive radio signalsoutside the first virtual carrier.

According to the present technique communications devices of differentcapabilities can be allocated communications resources within differentfrequency ranges according to their capability, which can relievecongestion on a centre frequency of communications resources in whichcommunications devices with a minimum bandwidth capability receivecommunications resources for receiving down link signals. This isbecause in some examples the centre frequencies include control channelswhich may be required to receive system information for communicatingvia the mobile communications network, such as synchronisation signalsand cell parameters etc.

It is expected in the future that there may be many devices which have areduced capability and which may be required to communicate within avirtual carrier bandwidth which may be less than the host bandwidth of amobile communications network such as a 4G or LTE network. Since thenumber of devices may be relatively large, a technical problem existsbecause the number of communications devices wishing to communicate viathe virtual carrier may produce congestion on, for example, a controlchannel or shared communications resources which are provided within thevirtual carrier.

Embodiments of the present disclosure are therefore directed to addressa technical problem of reducing an amount of congestion which may occurin a virtual carrier particularly in regard to a capacity of thecommunications channel. According to the embodiments of the presentdisclosure, a capacity of the virtual carrier is increased by providinga wireless access interface, which can exchange communications signalswith a communications device in which the communications device informsthe mobile network of its capability. Thus a communications device mayhave a different capability from other communications devices, andalthough operating in accordance with a reduced bandwidth capabilitymode, may be able to communicate that it has a capability to transmitand to receive radio signals outside a virtual carrier which is providedby the mobile communications network. Accordingly, if the communicationsdevice is capable of transmitting data to or receiving data from themobile communications network outside the virtual carrier then themobile network may allocate communications resources outside the virtualcarrier for this communications device.

According to this present technique therefore, communications devicesmay be determined as belonging to different classes corresponding todifferent capabilities for transmitting or receiving data. Thecapabilities may include one of a radio frequency bandwidth of atransmitter or a receiver or a base band bandwidth of a transmitter or areceiver to the effect that depending upon the capability of the device,a mobile communications network may allocate resources for communicatingvia the wireless access interface in accordance with the relativecapability of the device.

Further aspects and features of the present disclosure are defined inthe appended claims, including but not limited to, a mobilecommunications device, a method of communicating, a networkinfrastructure element, a communications network and the method ofcommunicating via a wireless access interface.

Various further aspects and embodiments of the disclosure are providedin the appended claims, including but not limited to, an infrastructureequipment, an infrastructure equipment, a communications device andmethod of receiving data from a mobile communications network element.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the present disclosure will now be described by way ofexample only with reference to the accompanying drawings in which likeparts are provided with corresponding reference numerals and in which:

FIG. 1 provides a schematic diagram illustrating an example of aconventional mobile communications system;

FIG. 2 provides a schematic diagram illustrating an arrangement ofchannels of a wireless access interface for ten down-link sub-frames ofa conventional LTE wireless access interface;

FIG. 3 provides a schematic diagram illustrating a conventional LTEdownlink radio sub-frame;

FIG. 4 provides a schematic diagram illustrating an LTE downlink radiosub-frame arranged to provide a narrow band virtual carrier includingcommunications resources within a bandwidth which is narrower than abandwidth of a host system;

FIG. 5 provides a schematic diagram illustrating an LTE downlink radiosub-frame arranged to provide a narrow band virtual carrier whichprovides for an allocation of communications resources from a frequencyrange which is outside that of the narrow band virtual carrier of FIG.4;

FIG. 6 provides a schematic diagram of an LTE downlink radio sub-framewhich illustrates a wireless access interface provided by a mobilecommunications network which includes allocating communicationsresources outside the narrow band virtual carrier for three possiblebandwidths including the narrow band virtual carrier;

FIG. 7 provides a schematic diagram of an LTE downlink radio sub-framewhich illustrates a wireless access interface provided by a mobilecommunications network which includes allocating communicationsresources for two classes of communications devices and includes adown-link control channel;

FIG. 8 is an example diagram representing a message exchange during anattach procedure according to the present technique;

FIG. 9 provides a schematic diagram of an LTE downlink radio sub-framewhich illustrates a wireless access interface provided by a mobilecommunications network which includes allocating communicationsresources for primary and secondary virtual carriers, which may beaggregated;

FIG. 10 provides a schematic diagram of an LTE downlink radio sub-framewhich illustrates a further example of wireless access interfaceprovided by a mobile communications network for the example shown inFIG. 9 in which a down-link control channel is provided for only theprimary virtual carrier;

FIG. 11 provides a schematic diagram of an LTE downlink radio sub-framewhich illustrates a further example of wireless access interfaceprovided by a mobile communications network which includes allocatingcommunications resources from an extended bandwidth where theseresources are accessible to a communications device;

FIG. 12 provides a schematic diagram of an LTE downlink radio sub-framewhich illustrates a further example of wireless access interfaceprovided by a mobile communications network which includes allocatingcommunications resources for primary and secondary virtual carriers;

FIG. 13 provides a schematic diagram of an LTE downlink radio sub-framewhich illustrates a further example of wireless access interfaceprovided by a mobile communications network which includes allocatingcommunications resources for primary and secondary virtual carriers andin which only the primary virtual carrier includes a downlink controlchannel resource;

FIG. 14 is a schematic block diagram of a mobile communications systemaccording to one example of the present technique;

FIG. 15 is a flow diagram illustrating the operation of a communicationsdevice (UE) according to the present technique; and

FIG. 16 is a flow diagram illustrating the operation of a mobilecommunications network according to the present technique.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Example Network

FIG. 1 provides a schematic diagram illustrating the basic functionalityof a conventional mobile communications system.

The network includes a plurality of base stations 101 connected to acore network 102. Each base station provides a coverage area 103 (i.e. acell) within which data can be communicated to and from communicationsdevices 104. Data is transmitted from a base station 101 to acommunications device 104 within a coverage area 103 via a radiodownlink. Data is transmitted from a communications device 104 to a basestation 101 via a radio uplink. The core network 102 routes data to andfrom the base stations 104 and provides functions such asauthentication, mobility management, charging and so on.

The term communications devices will be used to refer to acommunications terminal or apparatus which can transmit or receive datavia the mobile communications system. Other terms may also be used forcommunications devices such as personal computing apparatus, remoteterminal, transceiver device or user equipment (UE) which may or may notbe mobile.

Mobile telecommunications systems such as those arranged in accordancewith the 3GPP defined Long Term Evolution (LTE) architecture use anorthogonal frequency division multiplex (OFDM) based radio accessinterface for the radio downlink (so-called OFDMA) and the radio uplink(so-called SC-FDMA). Data is transmitted on the uplink and on thedownlink on a plurality of orthogonal sub-carriers. FIG. 2 shows aschematic diagram illustrating an OFDM based LTE downlink radio frame201. The LTE downlink radio frame is transmitted from an LTE basestation (known as an enhanced Node B) and lasts 10 ms. The downlinkradio frame comprises ten sub-frames, each sub-frame lasting 1 ms. Aprimary synchronisation signal (PSS) and a secondary synchronisationsignal (SSS) are transmitted in the first and sixth sub-frames of theLTE frame, in the case of frequency division duplex (FDD) system. Aphysical broadcast channel (PBCH) is transmitted in the first sub-frameof the LTE frame. The PSS, SSS and PBCH are discussed in more detailbelow.

FIG. 3 provides a schematic diagram providing a grid which illustratesthe structure of an example of a conventional downlink LTE sub-frame.The sub-frame comprises a predetermined number of symbols which aretransmitted over a 1 ms period. Each symbol comprises a predeterminednumber of orthogonal sub-carriers distributed across the bandwidth ofthe downlink radio carrier.

The example sub-frame shown in FIG. 3 comprises 14 symbols and 1200sub-carriers spaced across a 20 MHz bandwidth. The smallest unit onwhich data can be transmitted in LTE is twelve sub-carriers transmittedover one sub-frame. For clarity, in FIG. 3, each individual resourceelement is not shown, but instead each individual box in the sub-framegrid corresponds to twelve sub-carriers transmitted on one symbol.

FIG. 3 shows resource allocations for four LTE devices 340, 341, 342,343. For example, the resource allocation 342 for a first LTE device (UE1) extends over five blocks of twelve sub-carriers, the resourceallocation 343 for a second LTE device (UE2) extends over six blocks oftwelve sub-carriers and so on.

Control channel data is transmitted in a control region 300 of thesub-frame comprising the first n symbols of the sub-frame where n canvary between one and three symbols for channel bandwidths of 3 MHz orgreater and where n can vary between two and four symbols for channelbandwidths of 1.4 MHz. The data transmitted in the control region 300includes data transmitted on the physical downlink control channel(PDCCH), the physical control format indicator channel (PCFICH) and thephysical HARQ indicator channel (PHICH).

The PDCCH contains control data indicating which sub-carriers on whichsymbols of the sub-frame have been allocated to specific LTE devices.Thus, the PDCCH data transmitted in the control region 300 of thesub-frame shown in FIG. 3 would indicate that UE1 has been allocated thefirst block of resources 342, that UE2 has been allocated the secondblock of resources 343, and so on. In sub-frames where it istransmitted, the PCFICH contains control data indicating the duration ofthe control region in that sub-frame (i.e. between one and four symbols)and the PHICH contains HARQ (Hybrid Automatic Request) data indicatingwhether or not previously transmitted uplink data has been successfullyreceived by the network.

In certain sub-frames, symbols in a central band 310 of the sub-frameare used for the transmission of information including the primarysynchronisation signal (PSS), the secondary synchronisation signal (SSS)and the physical broadcast channel (PBCH). This central band 310 istypically 72 sub-carriers wide (corresponding to a transmissionbandwidth of 1.08 MHz). The PSS and SSS are synchronisation signals thatonce detected allow the LTE device 104 to achieve frame synchronisationand determine the cell identity of the enhanced Node B transmitting thedownlink signal. The PBCH carries information about the cell, comprisinga master information block (MIB) that includes parameters that the LTEdevices require to access the cell. Data transmitted to individual LTEdevices on the physical downlink shared channel (PDSCH) can betransmitted in the remaining blocks of communications resource elementsof the sub-frame. Further explanation of these channels is provided inthe following sections.

FIG. 3 also shows a region of PDSCH containing system information andextending over a bandwidth of R₃₄₄. Thus in FIG. 3 the central frequencycarries control channels such as the PSS, SSS and PBCH and thereforeimplies a minimum bandwidth of a receiver of a communications device.

The number of sub-carriers in an LTE channel can vary depending on theconfiguration of the transmission network. Typically this variation isfrom 72 sub carriers contained within a 1.4 MHz channel bandwidth to1200 sub-carriers contained within a 20 MHz channel bandwidth as shownin FIG. 3. As is known in the art, subcarriers carrying data transmittedon the PDCCH, PCFICH and PHICH are typically distributed across theentire bandwidth of the sub-frame. Therefore a conventional LTE devicemust be able to receive the entire bandwidth of the sub-frame in orderto receive and decode the control region.

Virtual Carrier

Certain classes of devices, such as MTC devices (e.g. semi-autonomous orautonomous wireless communication devices such as smart meters asdiscussed above), support communication applications that arecharacterised by the transmission of small amounts of data at relativelyinfrequent intervals and can thus be considerably less complex thanconventional LTE devices. Communications devices may include ahigh-performance LTE receiver unit capable of receiving and processingdata from an LTE downlink frame across the full carrier bandwidth.However, such receiver units can be overly complex for a device whichonly needs to transmit or to receive small amounts of data. This maytherefore limit the practicality of a widespread deployment of reducedcapability MTC type devices in an LTE network. It is preferable insteadto provide reduced capability devices such as MTC devices with a simplerreceiver unit which is more proportionate with the amount of data likelyto be transmitted to the device. Furthermore, as explained above it isdesirable to include features in a mobile communications network and/orcommunications devices which can conserve power consumption of thecommunications devices.

In conventional mobile telecommunication networks, data is typicallytransmitted from the network to the communications devices in afrequency carrier (first frequency range) where at least part of thedata spans substantially the whole of the bandwidth of the frequencycarrier. Normally a communications device cannot operate within thenetwork unless it can receive and decode data spanning the entirefrequency carrier, i.e. a maximum system bandwidth defined by a giventelecommunication standard, and therefore the use of communicationsdevices with reduced bandwidth capability transceiver units isprecluded.

However, as disclosed in co-pending International patent applicationsnumbered PCT/GB2012/050213, PCT/GB2012/050214, PCT/GB2012/050223 andPCT/GB2012/051326, the contents of which are herein incorporated byreference, a subset of the communications resource elements comprising aconventional carrier (a “host carrier”) are defined as a “virtualcarrier”, where the host carrier has a certain bandwidth (host frequencybandwidth) and where the virtual carrier has a reduced bandwidth(virtual carrier frequency bandwidth) compared to the host carrier'sbandwidth. Data for reduced capability devices is separately transmittedon the virtual carrier set of communications resource elements.Accordingly, data transmitted on the virtual carrier can be received anddecoded using a reduced complexity or capability transceiver unit.

Devices provided with reduced complexity or capability transceiver units(hereafter referred to as “reduced capability devices”) could operate byusing a part of its full capability (i.e. reduced capability set of itsfull capability) or they could be constructed to be less complex andless expensive than conventional LTE type devices (onwards referred togenerally as LTE devices). Accordingly, the deployment of such devicesfor MTC type applications within an LTE type network can become moreattractive because the provision of the virtual carrier allowscommunications devices with less expensive and less complex transceiverunits to be used.

Dynamic Allocation of Resources to Different Capability Receivers

Embodiments of the present technique can provide an arrangement in whicha mobile communications network is configured to allocate communicationsresources which are outside a certain core frequency range, which formsa virtual carrier for reduced capability devices. However according tothe present technique different classes of mobile communications devicesare configured to communicate using the mobile communications network.As explained above, the mobile communications network including one ormore network elements provides a wireless access interface for thecommunications devices. The wireless access interface provides aplurality of communications resource elements across a host frequencyrange, and at least one section of frequency resources within the hostfrequency band within a first frequency band, which forms a virtualcarrier for reduced capability devices. The virtual carrier provides aplurality of communications resources for preferable allocation to thecommunications devices for receiving signals transmitted or receivedwithin the first frequency band.

According to the present technique, the communications device isconfigured to transmit to the mobile communications network a relativecapability of the communications device to transmit or receive data viathe wireless access interface, the relative capability comprising atleast an indication of a bandwidth of the receiver. The mobilecommunications network responds by allocating communications resourcesoutside the first virtual carrier in response to an indication that therelative capability of the device is such that the device can receive ortransmit via the wireless access interface in communications resourceswhich are outside the frequency range of the virtual carrier.

Embodiments of the present technique are therefore configured to providean arrangement in which a communications device can select a supportingvirtual carrier bandwidth which is less than the full bandwidth of thehost system, but maybe different per communications device, according toits complexity and capability, data rate, etc. From the network side, aninfrastructure element such as an eNodeB can be arranged to allocatecommunications resources within the wide system bandwidth according tothe supported bandwidth signalled from the communications terminals.Accordingly, the present technique can provide for a flexible selectionof supporting bandwidth for communications devices so that these devicescan:

-   -   Enable the reuse of the PSS/SSS/PBCH in the host carrier for MTC        devices    -   Provide more resource to MTC devices outside centre frequency,        so as to reduce congestion on the centre frequencies;    -   Reduce the cost of MTC devices compared to legacy communications        devices by reducing the supported RF/Baseband bandwidth (basic        merit of a virtual carrier arrangement)

FIG. 4 provides an example illustration which corresponds to that shownin FIG. 3 but with the virtual carrier forming a centre frequency of thewireless access interface and in which the sub-frame comprises two timeslots delineated by a vertical line 501. As can be seen from FIG. 4,data transmitted on the virtual carrier 502 is transmitted across alimited bandwidth. This could be any suitable bandwidth providing it issmaller than that of the host carrier, which for example is 20 MHz. Inthe example shown in FIG. 4 the virtual carrier is transmitted across abandwidth comprising resource blocks and sub-carriers which isequivalent to a 1.4 MHz transmission bandwidth. Accordingly, a devicereceiving data transmitted on the virtual carrier need only be equippedwith a receiver capable of receiving and processing data transmittedover a bandwidth of 1.4 MHz. This enables reduced capability devices(for example MTC type devices) to be provided with simplified receiverunits yet still be able to operate within an OFDM type communicationnetwork which, as explained above, conventionally requires devices to beequipped with receivers capable of receiving and processing an OFDMsignal across the entire bandwidth of the signal. In keeping with aconventional LTE downlink sub-frame, the first n symbols (n is three inFIG. 4) form the control region 300 is reserved for the transmission ofdownlink control data such as data transmitted on the PDCCH.

As explained above, the centre frequencies may be an advantageouslocation to allocate a virtual carrier within a host carrier. This isbecause the Primary and Secondary Synchronization Signals (PSS/SSS) andPhysical Broadcast Channel (PBCH) are located in the centre frequencyand therefore can be more easily acquired by MTC communications devices,which can only receive the virtual carrier and so can reuse thesePSS/SSS/PBCH channels. However, if MTC devices can only be allocatedresources from a virtual carrier occupying the centre frequencies, thenthe resources of those centre frequencies may become congested.Accordingly the present technique can provide an arrangement forallocating resources from other parts of the host carrier wirelessaccess interface in accordance with a capability of the devices. SuchMTC devices may still be operating in a virtual carrier mode, receivingan allocation of resources, which are reserved or predetermined forallocation to MTC-type devices.

As explained above embodiments of the present technique have beenprovided to increase the bandwidth of a shared resource which may beallocated to communications devices which may have a differentcapability which may be less than the full capability so that whilstthese devices can communicate within a predetermined frequency rangethey cannot communicate via the full bandwidth of the host system. Thus,as illustrated in FIG. 5 which corresponds to the diagram shown in FIG.4 a separate frequency range 600 which is less than the host bandwidthof the wireless access interface is provided for allocation to reducecapability devices for classes of devices which can communicate within agreater frequency bandwidth than the virtual carrier bandwidth of thevirtual carrier 502 shown in FIG. 4. Thus, as shown in FIG. 5 a virtualcarrier control channel VC-PDCCH 602 is provided with an SS/PBCH 604which corresponds to the examples shown in FIGS. 3 and 4 but areavailable to communications devices which can communicate in frequencieswhich are outside the virtual carrier bandwidth 530 of FIG. 4.

Embodiments of the present technique can therefore be viewed, in someexamples, as a wider bandwidth virtual carrier, which is narrower thanthe host system bandwidth, with supporting bandwidth altered flexiblyper communications devices. Furthermore, the common information that areintended to all VC UEs such as the broadcast information and controlinformation (VC-PDCCH) have to be sent at the narrowest possiblebandwidth so that all VC UEs are able to receive them.

An example embodiment of the present technique is illustrated in FIG. 6in which a wireless access interface corresponding to that shown inFIGS. 4 and 5 is shown but illustrating an operation in which threeclasses of communications terminals are operating within the mobilecommunications network. As shown in FIG. 6, the virtual carrier, shownin FIG. 5, 530 is provided by the wireless access interface with thevirtual carrier control channel 602 and the SS/BPCH 604 provided forcommunications terminals which can only communicate within the frequencybandwidth of the virtual carrier. Thus, reduced capability terminals ofa first class (Class A) transmit requests for allocations of resourceson the shared channel which are communicated on the downlink to allocateto the communications devices within the VC-PDCCH 602 and are allocatedthose shared resources within the virtual carrier bandwidth 530 incommunications resources 702, 704. The central region provides thelowest available bandwidth which can be supported because this alsoincludes the other control channels mentioned above (SS/PBCH).

According to the present technique there are other classes ofcommunications terminals other than class A which can only communicatewithin the smallest bandwidth of a virtual carrier 530 for class A. Asshown in FIG. 6, two other classes, class B and class C are illustratedwhich are able to communicate within communications resources within twowider bandwidths 732, 734. Thus, within the bandwidth 732 of the class Bdevices, communications resources are allocated to the class B deviceswithin the second largest bandwidth 732. Accordingly, the class Bbandwidth 732 provides a reserved set of communications resources, forpreferable allocation within an extension of the virtual carrierbandwidth 530 to provide a shared communications resource for the classB devices within a frequency band 740. Communications devices aretherefore capable of communicating within the second largest bandwidth732. Similarly, for a class C device which is able to receive signalsfrom within a bandwidth which is larger than the class B and class Adevices 734, a separate band of communications resources within asection of the wireless access interface 742 is provided which areallocated to class C communications devices by the mobile communicationsnetwork. Thus, a class C device may request downlink communicationsresources and may be allocated downlink communications resources byreceiving a control channel signal from the virtual carrier downlinkcontrol channel VC-PDCCH 602. The down-link control channel VC-PDCCH 602may allocate downlink communications resources within the bandwidth 734for class C devices which may include the separate shared communicationsresources VC-PDSCH for class C devices 742 and may also includecommunications resources within the second class B shared channel 740 aswell as the class A channel 530.

Accordingly, as will be appreciated from the example given in FIG. 6,there are various classes of devices, each class representing abandwidth which that device can either transmit or receivecommunications resources and therefore the mobile network allocatescommunications resources in correspondence with the class of device andthe ability of the devices within that class to receive downlinkcommunications from different bandwidths than the virtual carrier. Thusaccording to the example shown in FIG. 6, a communications device ofclass A (class A UE) has the minimum capability and only supports 1.4MHz. When an eNodeB sends data to this device (UE A), it makes sure thatthe resource allocated to it is within the centre 1.4 MHz. In contrast adevice from class B (UE B) may support a larger bandwidth of 3 MHz, inwhich case, the eNodeB can allocate a 3 MHz wide resource to thisdevice. In one example, the bandwidth of VC-PDCCH 602 needs to bereceivable by all classes of devices operating under the virtual carriersystem, and so needs to be limited to the narrowest maximum bandwidththat the MTC-type devices need to support (which is 1.4 MHz in the abovecase), so all MTC devices can properly receive this common information.

In other example embodiments of the present technique, the down-linkcontrol channel for allocating the communications resources of theshared channel to the communications device is a so-called enhanceddown-link control channel or an ePDCCH-like design, which is applied tothe virtual carrier arrangement (VC-PDCCH). Such embodiments can have anadvantage because the common control information (VC-PDCCH) which needsto be read by all classes of devices is narrow bandwidth in nature.

A further example is shown in FIG. 7. In FIG. 7, two classes of devicesare identified as being able to communicate via first and secondfrequency bands 802, 804. However, unlike the examples shown in FIG. 6in which the downlink resources are allocated by communicating resourceallocation messages in a VC-PDCCH 602, the example shown in FIG. 7provides a so-called enhanced downlink control channel ePDCCH which isprovided within a separate bandwidth 806 and extends substantially fromthe downlink control channel of the host carrier 300, across two exampleframes of the wireless access interface 504, 506. This enhanced downlinkcontrol channel (ePDCCH) is provided to allocate communicationsresources, which is narrow in frequency but wide in time in contrast tothe host PDCCH which is narrow in time but wide in frequency. A secondclass of communications devices class B is able to allocate in a widerbandwidth 804 within the host communications bandwidth 810 and so can beallocated shared channel resources within an extended region 812(VC-PDSCH (for UE B)). In contrast the class A devices can only beallocated shared communications resources within the class A bandwidth802 within the shared resources provided by class A devices 818.Accordingly, for the examples shown in FIG. 7, downlink control messagesare communicated by the ePDCCH 806 which occupies a narrow bandwidthfrequency but an entire duration of one subframe (two slots) which wouldotherwise be occupied by shared channel resources for communicatingdownlink control channel messages to for both class A and class Bcommunications devices. In this example, the class A and class B devicescan receive downlink control link messages from the ePDCCH 806 forallocating shared channel communications resources within the twodifferent bandwidths 802, 804. Thus class A devices receive bandwidthallocations within the smaller bandwidth 802 that is within the sharedresources 818, whereas although class B devices also receive downlinkcontrol channel resource allocation messages from the ePDCCH 806, theseclass B devices may be allocated communications resources for downlinkcommunication within both the class A bandwidth 818 and the class Bbandwidth 812.

Communications devices (UEs) operating in accordance with the presenttechnique are arranged to exchange information with the mobilecommunications network in order to identify which class of a pluralityof classes of reduced capability devices the communications devicebelongs. As illustrated above, with the three classes, class A, class B,class C each class corresponds to a predetermined bandwidth within whichthe communications device can receive for example downlinkcommunications signals within a shared resource. According the presenttechnique therefore, a communications device exchanges messages with themobile communications network in order to identify which class thedevice belongs. The messages identify at least a bandwidth of thecommunications device within which the communications device can receivedownlink signals and therefore can be allocated downlink sharedresources within that bandwidth. An example arrangement in which thecommunications device sends and receives messages from the mobilenetwork in order to establish which class the device belongs is shown inFIG. 8.

In FIG. 8 in step 1 a communications device transmits a request toaccess the communications resources of the wireless access interface.For example, the request to access the communications resources may bean attach procedure in which the communications device first powers onand attaches to the mobile network by being affiliated with a particularbase station which may be an eNodeB. Thus, in step 1 a request to accessthe communications resources is sent to the base station eNodeB. Inresponse, the mobile network communicates a request to identify acapability of the communications device in step 2. In step 3 the mobilecommunications device responds by indicating which class thecommunications device belongs. For example, this could be a field in amessage sent as part of an attach procedure to the mobile communicationsnetwork which may include a field identifying which of the classes thecommunications device belongs. In response, the eNodeB grantscommunications resources in step 4 by communicating the resources whichare allocated to the communications device (UE) in correspondence with acapability of a device from the class of that device.

Primary and Secondary Virtual Carrier Examples

Further example of embodiments of the present technique are illustratedwith reference to FIGS. 9 to 13 in which a wireless access interface isprovided with at least a primary and a secondary virtual carrier withina host carrier. FIG. 9 provides an illustration of such a situationwhich corresponds to the example shown in FIG. 5. However, from theexample shown in FIG. 9, two virtual carriers have been provided withina maximum bandwidth available to communications devices 900. Thus, asshown in FIG. 11 alongside the downlink control channel for the hostcarrier 300, two virtual carriers are provided 902, 904 in which each isprovided with a separate downlink control channel 906, 908 forcommunicating resource allocation messages to communications devicesallocating downlink shared resources within a first downlink sharedvirtual carrier VC-PDSCH 910. The first downlink shared virtual carrierVC-PDSCH 910 is a primary shared resource with a first set ofcommunications resources for preferable allocation to reduced capabilitydevices. Also shown for the example embodiment of FIG. 9 is a secondaryshared resource 912 within the second virtual carrier 904. Thearrangement shown in FIG. 9 therefore provides an example in which twovirtual carriers exist and are hosted by a mobile communicationsnetwork, which may be supported outside a centre frequency andconfigured identically to the primary virtual carrier without thecentral control channels PSS/SSS/PBCH, but includes a VC-PDCCH from theprimary virtual carrier. Embodiments of the present technique thereforeprovide an arrangement for more resource to be allocated for MTC-typedevices, which can therefore reduce congestion on the centre frequencyor primary virtual carrier using virtual carrier aggregation. This isbecause a communications device which has a maximum bandwidth 900 canuse either of the virtual carriers 902, 904.

Embodiments of the present technique can also provide an advantage byreducing the cost of the different classes of MTC-type devices comparedto conventional full-bandwidth devices, because the maximum supportedbandwidth could be reduced to (highest frequency relevant to aterminal—lowest frequency relevant to a terminal). This advantage couldbe particularly applicable where a network operator and a devicemanufacturer can collaborate to ensure such bandwidths are allocated.

As will be appreciated although the arrangements shown in FIG. 9provides a separate downlink control channel for allocating resourceswithin the shared channel for the second virtual carrier 904, thebalance of communications resources to the control channels forcommunicating resource allocation message with respect to the sharedchannel resources means that some capacity can be underutilised in thatthe second downlink shared channel 908 of the second virtual carrier904. Accordingly, an alternative arrangement is shown in FIG. 10 inwhich the second virtual carrier 904 does not include a separatedownlink control channel 908. For this example, therefore, a downlinkcontrol channel of the primary virtual carrier 902 (VC-PDCCH 1006) isarranged to allocate shared resources to a communications device with anoperating bandwidth 900 as illustrated by arrows 950, 952. Thus, incontrast the examples shown in FIG. 9 an aggregated arrangement ofvirtual carriers is provided in which a downlink control channel 1006provided on the centre frequencies of the primary virtual carrier 902allocates communications resources which are shared in both the primaryvirtual carrier 902 and the secondary virtual carrier 904 which forms acombined shared channel resource for reduced capability devicescomprising regions 954, 956. According to the example shown in FIG. 10,not only are the PSS/SSS/PBCH control channels provided in the primaryvirtual carrier but also the down-link control channel for allocatingthe shared channel resources (VC-PDCCH). This may allow for moreflexible and efficient resource allocation.

A further example is illustrated in FIG. 11 which corresponds to theexample shown in FIG. 10 except that the secondary virtual carrier 950,960 is allocated within a central region close to or contiguous with theprimary virtual carrier. According to this example embodimentcommunications resources can be allocated to communications devices witha lower operating bandwidth 980 compared to that shown in FIG. 10. Aswill be appreciated from the example shown in FIG. 11, a communicationsdevice with an operating bandwidth 980 could be allocated shared channelresources from a secondary bandwidth 950 or a secondary bandwidth 960which is below that of the virtual carrier in the centre bandwidth whichis the primary virtual carrier 902. Accordingly, the arrangement shownin FIG. 11 provides some additional flexibility. This is because, byproviding this arrangement from the wireless communications bandwidththe location of secondary virtual carrier resources can reduce a maximumsupported bandwidth of a communications devices which is required to VCBandwidth x (n+1) where n is the number of contiguously-placed secondaryvirtual carriers that the communications device can support.

Further examples of the present technique are illustrated in FIGS. 12and 13. In FIGS. 12 and 13 a first and a secondary virtual carrier isprovided 1000, 1001 in which each has a narrow band but wide durationdownlink control channel 1002, 1004 (VC-PDCCH) and shared channelresources (VC-PDSCH) within a remaining part of the operating bandwidth1006, 1008, 1010, 1012. Thus, for the example shown in FIG. 12, twoseparate virtual carriers are provided, each of which has a so-calledenhanced downlink control channel VC-ePDCCH which communicates downlinkresource allocation messages to the communications terminals which areable to communicate within the primary virtual carrier 1000 or thesecondary virtual carrier 1001. However, again from the exampleillustrated with reference to FIGS. 10 and 11, there could be anover-capacity in downlink control channel resources compared to those ofthe shared channel resources. Accordingly, in FIG. 13, the secondaryvirtual carrier 1001 has been adapted to remove a downlink controlchannel 1004 of the secondary virtual carrier, so that the secondaryvirtual carrier 1100 contains only shared channel resources (VC-PDSCH)whereas the primary virtual carrier 1000 corresponds substantially tothe example shown in FIG. 12. Again, according to this example thedownlink control channel which is allocated resource allocation messagesfor downlink resources in the primary virtual carrier 1000, 1002allocates resources within the secondary virtual carrier 1100 or theremaining shared channel resources within the primary virtual carrier1000 as illustrated by resource allocation indicated as arrows 1004,1006. Accordingly, there is an improvement in the efficiency with whichthe resources of the wireless access interface are used because there isa relative reduction in the capacity given to downlink control channelresources and an increase in the shared channel resources by removingthe enhanced downlink shared channel from the secondary virtual carrierfrom 1100.

Example Mobile Communications System

FIG. 14 provides a schematic diagram showing part of an adapted LTEmobile communications system. The system includes an adapted enhancedNode B (eNB) 1401 connected to a core network 1408 which communicatesdata to a plurality of conventional LTE devices 1402 and reducedcapability devices 1403 within a coverage area (i.e. cell) 1404. Each ofthe reduced capability devices 1403 has a transceiver unit 1405 whichincludes a receiver unit capable of receiving data across a reducedbandwidth and a transmitter unit capable of transmitting data across areduced bandwidth (or full bandwidth of an uplink carrier supported bythe eNB 1401) when compared with the capabilities of the transceiverunits 1406 included in the conventional LTE devices 1402.

The adapted eNodeB 1401 is arranged to transmit downlink data using asub-frame structure that includes a virtual carrier as described abovefor example with reference to FIGS. 4 to 13. A transmitter and receiverunit 1409 forms a wireless access interface under the control of acontroller 1411, which also performs the function of an adaptedscheduler. The reduced capability devices 1403 are thus able to receiveand transmit data using the uplink and/or downlink virtual carriers asdescribed above and may be considered as comprising different classes ofdevices. Each class may have a different bandwidth capability, which canprovide an arrangement for allocating resources outside the virtualcarrier or conceptually an extended virtual carrier.

As has been explained above, because the reduced complexity devices 1403receive data across a reduced bandwidth downlink virtual carriers, thecomplexity, power consumption and cost of the transceiver unit 1405needed to receive and decode downlink data and to encode and transmituplink data is reduced compared to the transceiver unit 1406 provided inthe conventional LTE devices.

When receiving downlink data from the core network 1408 to betransmitted to one of the devices within the cell 1404, the adaptedeNodeB 1401 is arranged to determine if the data is bound for aconventional LTE device 1402 or a reduced capability device 1403. Thiscan be achieved using any suitable technique. For example, data boundfor a reduced capability device 1403 may include a virtual carrier flagindicating that the data must be transmitted on the downlink virtualcarrier. If the adapted eNodeB 1401 detects that downlink data is to betransmitted to a reduced capability device 1403, a controller 1411included in the adapted eNodeB 1401 ensures that the downlink data istransmitted to the reduced capability device in question on the downlinkvirtual carrier. In another example the network is arranged so that thevirtual carrier is logically independent of the eNodeB. Moreparticularly the virtual carrier can be arranged to appear to the corenetwork as a distinct cell. From the perspective of the core network itis not known that the virtual carrier is physically co-located with, orhas any interaction with, the host carrier of the cell. Packets arerouted to/from the virtual carrier just as they would be for any normalcell.

The operation of a communications device according to the presenttechnique is summarised by the flow diagram in FIG. 15, which issummarised as follows:

S1: A communications device determines which of a plurality of classesthe communications device belongs. Each class represents at least adifferent bandwidth capability of a transmitter or a receiver of thedevice. The allocation of the class to a device can be determined by thenetwork during an initial attach procedure or may be predetermined by anetwork operator and pre-stored in the device.

S2: The communications device transmits to the mobile communicationsnetwork the relative capability of the communications device to receivedata via a wireless access interface provided by the mobile accessnetwork. The relative capability according to the allocated class ofdevice includes at least an indication of a bandwidth of thecommunications device.

S4: The communications device receives a resource allocation messagefrom the mobile communications network which allocates sharedcommunications resources within a bandwidth corresponding to thepredetermined class of the communications device. The allocatedresources may be outside the bandwidth of the virtual carrier or may bean extension of the virtual carrier.

The operation of a network device such as a mobile communicationsinfrastructure equipment is illustrated by the example provided in FIG.16 and summarised as follows:

S6: A network infrastructure equipment (e.g. eNodeB) provides a wirelessaccess interface for transmitting data to and receiving data from mobilecommunications devices using a transmitter and a receiver. The wirelessaccess interface provides a plurality of communications resourceelements across a host frequency bandwidth, and includes at least onesection of communications resources for preferable allocation to reducedcapability devices within a virtual carrier bandwidth. The virtualcarrier bandwidth is within the host frequency bandwidth, thecommunications resources within the virtual carrier bandwidth beingprovided for preferable allocation to communications devices to receivesignals representing the data transmitted within the virtual carrierbandwidth so as to form a virtual carrier.

S8: The network infrastructure equipment receives from a communicationsdevice a relative capability of the communications device. The relativecapability can be provided as an indication of a class to which thedevice belongs and indicates an ability to receive signals representingthe data via the wireless access interface, and indicates at least abandwidth of the communications device to receive the signals.

S10: The network infrastructure equipment allocates communicationsresources outside the the first virtual carrier, but within thebandwidth of the communications device, in response to the indication ofthe relative capability of the communications device.

Various further aspects and features of the present disclosure aredefined in the appended claims. Various combinations of the features ofthe dependent claims may be made with those of the independent claimsother than the specific combinations recited for the claim dependency.Embodiments of the present disclosure have been defined largely in termsof reduced capability devices transmitting data via a virtual carrierinserted in a conventional LTE based host carrier. However, it will beunderstood that any suitable device can transmit and receive data usingthe described virtual carriers for example devices which have the samecapability as a conventional LTE type device or devices which haveenhanced capabilities.

Further examples of the present technique include an infrastructureequipment or network element for forming part of a mobile communicationsnetwork comprising a transmitter unit configured to transmit data tocommunications devices via a wireless access interface, a receiver unitconfigured to receive data transmitted from communications devices viathe wireless access interface, and a controller. The controller isconfigured to control the transmitter unit and the receiver unit to formthe wireless access interface providing a plurality of communicationsresource elements across a host frequency bandwidth, and including,within the host frequency bandwidth, a first section of communicationsresource elements within a first frequency bandwidth for allocationpreferably to reduced capability devices to receive signals representingthe data transmitted by the transmitter unit within the first bandwidthforming a first virtual carrier, the reduced capability devices eachhaving a receiver bandwidth which is greater than or equal to the firstfrequency bandwidth but less than the host frequency bandwidth. Thecontroller is configured in combination with the transmitter unit andthe receiver unit to receive from a communications device a relativecapability of the communications device to receive signals representingthe data via the wireless access interface, the relative capabilitycomprising at least an indication of a relative bandwidth of thecommunications device to receive the signals within the host frequencyrange greater than or equal to the first bandwidth, and to allocatecommunications resource elements which include communications resourceelements which are outside the first frequency bandwidth, but within thebandwidth of the communications device, in response to the indication ofthe relative capability of the communications device.

In one example the infrastructure equipment allocates the communicationsresource elements outside the first bandwidth to the communicationsdevice in dependence upon a capacity of the first virtual carrier and ademand on the communications resource elements of the first virtualcarrier by the reduced capability devices. The controller in combinationwith the transmitter unit and the receiver unit may be configured toreceive signals from and/or transmit signals to communications devicesin accordance with a one of a predetermined set of classes ofcommunications devices, each class defining a different frequencybandwidth within which the communications device can receive signalsfrom the infrastructure equipment, and to transmit a resource allocationmessage to the communications device which allocates sharedcommunications resource elements to the communications device within abandwidth corresponding to one of a predetermined number of classes ofthe communications device.

Furthermore the controller may be configured in combination with thereceiver unit to receive from one of the communications devices theclass of the communications device from one of the predeterminedclasses, each class defining a different frequency bandwidth withinwhich the communications device can receive signals from the wirelessaccess interface.

The following numbered clauses provide further example aspects andfeatures of the present technique:

1. An infrastructure equipment for forming part of a mobilecommunications network, the infrastructure equipment comprising:

a transmitter unit configured to transmit data to communications devicesvia a wireless access interface,

a receiver unit configured to receive data transmitted fromcommunications devices via the wireless access interface, and acontroller configured to control the transmitter unit and the receiverunit to form the wireless access interface providing a plurality ofcommunications resource elements across a host frequency bandwidth, andincluding, within the host frequency bandwidth, a first section ofcommunications resource elements within a first frequency bandwidth forallocation preferably to reduced capability devices to receive signalsrepresenting the data transmitted by the transmitter unit within thefirst bandwidth forming a first virtual carrier, the reduced capabilitydevices each having a receiver bandwidth which is greater than or equalto the first frequency bandwidth but less than the host frequencybandwidth, and the controller is configured in combination with thetransmitter unit and the receiver unit

to receive from a communications device a relative capability of thecommunications device to receive signals representing the data via thewireless access interface, the relative capability comprising at leastan indication of a relative bandwidth of the communications device toreceive the signals within the host frequency range greater than orequal to the first bandwidth, and

to allocate communications resource elements which includecommunications resource elements which are outside the first frequencybandwidth, but within the bandwidth of the communications device, inresponse to the indication of the relative capability of thecommunications device.

2. An infrastructure equipment according to clause 1, wherein theinfrastructure equipment allocates the communications resource elementsoutside the first bandwidth to the communications device in dependenceupon a capacity of the first virtual carrier and a demand on thecommunications resource elements of the first virtual carrier by thereduced capability devices.

3. An infrastructure equipment according to clause 1 or 2, wherein thecontroller in combination with the transmitter unit and the receiverunit are configured

to receive signals from and/or transmit signals to communicationsdevices in accordance with a one of a predetermined set of classes ofcommunications devices, each class defining a different frequencybandwidth within which the communications device can receive signalsfrom the infrastructure equipment, and

to transmit a resource allocation message to the communications devicewhich allocates shared communications resource elements to thecommunications device within a bandwidth corresponding to one of apredetermined number of classes of the communications device.

4. An infrastructure equipment according to clause 3, wherein thecontroller is configured in combination with the receiver unit

to receive from one of the communications devices the class of thecommunications device from one of the predetermined classes, each classdefining a different frequency bandwidth within which the communicationsdevice can receive signals from the wireless access interface.

5. An infrastructure equipment according to clause 4, wherein thecontroller is configured in combination with the transmitter unit andthe receiver unit

to transmit in response to receiving a request to attach to the mobilecommunications network a request to communicate an indication of theclass to which the communications device belongs, and

to receive in response to the transmitted request for the class of thecommunications device an indication of the class of the communicationsdevice.

6. An infrastructure equipment according to any of clauses 1 to 5,wherein the controller is configured in combination with the transmitterunit and the receiver unit

to form the wireless access interface with a second virtual carrierproviding a second section of communications resource elements forpreferable allocation to the reduced capability devices within a secondbandwidth, within the host frequency bandwidth of the wireless accessinterface,

to transmit signalling information providing the location of the secondvirtual carrier, and

in accordance with a capability of the communications devices, totransmit signals representing data to one of the communications devicesfrom communications resource elements of the second virtual carrier andthe first virtual carrier.

7. An infrastructure equipment according to clause 6, wherein thecontroller is configured in combination with the transmitter unit andthe receiver unit

to form the wireless access interface with the first virtual carrier,which includes a control channel for communicating messages to thecommunications device to allocate communications resource elements ofthe first and second virtual carriers, and

to transmit a resource allocation message on the control channel to thecommunications device, the resource allocation message allocatingcommunications resource elements within the first and second virtualcarriers, and

to transmit signals from the allocated communications resource elementsof the first and second virtual carriers to the reduced capabilitycommunications devices.

8. An infrastructure equipment according to any of clauses 1 to 7,wherein the first virtual carrier is located substantially at centre ofthe host frequency bandwidth.

9. An infrastructure equipment according to clause 8, wherein the firstvirtual carrier bandwidth includes one or more other control channelsfor providing other control information, and the controller isconfigured in combination with the receiver unit to receive othercontrol information from the other control channels.

10. A method of communicating with a communications device from aninfrastructure equipment for forming part of a mobile communicationsnetwork, the method comprising:

transmit data to communications devices via a wireless access interface,and

receiving data transmitted from communications devices via the wirelessaccess interface, the wireless access interface providing a plurality ofcommunications resource elements across a host frequency bandwidth, andincluding, within the host frequency bandwidth, a first section ofcommunications resource elements within a first frequency bandwidth forallocation preferably to reduced capability devices to receive signalsrepresenting the data transmitted by the transmitter unit within thefirst bandwidth forming a first virtual carrier, the reduced capabilitydevices each having a receiver bandwidth which is greater than or equalto the first frequency bandwidth but less than the host frequencybandwidth, and

receiving from a communications device a relative capability of thecommunications device to receive signals representing the data via thewireless access interface, the relative capability comprising at leastan indication of a relative bandwidth of the communications device toreceive the signals within the host frequency range greater than orequal to the first bandwidth, and

allocating communications resource elements which include communicationsresource elements which are outside the first frequency bandwidth, butwithin the bandwidth of the communications device, in response to theindication of the relative capability of the communications device.

11. A method according to clause 10, wherein the allocatingcommunications resource elements outside the first frequency range ofthe first virtual carrier comprises allocating the communicationsresource elements outside the first virtual carrier to thecommunications device in dependence upon a capacity of the first virtualcarrier and a demand on the communications resource elements of thefirst virtual carrier by the reduced capability devices.

12. A method according to clause 10 or 11, wherein the allocatingcommunications resource elements which include communications resourceelements which are outside the first frequency bandwidth comprises

receiving signals from and/or transmitting signals to communicationsdevices in accordance with a one of a predetermined set of classes ofcommunications devices, each class defining a different frequencybandwidth within which the communications device can receive signalsfrom the infrastructure equipment, and

transmitting a resource allocation message to the communications devicewhich allocates shared communications resource elements to thecommunications device within a bandwidth corresponding to one of apredetermined number of classes of the communications device.

13. A method according to clause 12, wherein the allocatingcommunications resources outside the first virtual carrier comprises

receiving from one of the communications devices the class of thecommunications device from one of the predetermined classes, each classdefining a different frequency bandwidth within which the communicationsdevice can receive signals from the wireless access interface.

14. A method according to clause 13, wherein the receiving from one ofthe communications devices the class of the communications device fromone of the predetermined classes comprises

transmitting in response to receiving a request to attach to the mobilecommunications network a request to communicate an indication of theclass to which the communications device belongs, and

receiving in response to the transmitted request for the class of thecommunications device an indication of the class of the communicationsdevice.

15. A method according to any of clauses 10 to 14, wherein theallocating communications resources outside the first virtual carriercomprises

forming the wireless access interface with a second virtual carrierproviding a second section of communications resource elements forpreferable allocation to the reduced capability devices within a secondbandwidth, within the host frequency bandwidth of the wireless accessinterface,

transmitting signalling information providing the location of the secondvirtual carrier, and

in accordance with a capability of the communications devices,transmitting signals representing data to one of the communicationsdevices from communications resource elements of the second virtualcarrier and the first virtual carrier.

16. A method according to clause 14 or 15, wherein the forming thewireless access interface with the first virtual carrier, comprises

forming the wireless access interface with the first virtual carrier,which includes a control channel for communicating messages to thecommunications device to allocate communications resource elements ofthe first and second virtual carriers,

transmitting a resource allocation message on the control channel to thecommunications device, the resource allocation message allocatingcommunications resource elements within the first and second virtualcarriers, and

transmitting signals from the allocated communications resource elementsof the first and second virtual carriers to the reduced capabilitycommunications devices.

17. A method according to any of clauses 10 to 16, wherein the firstvirtual carrier is located substantially at centre of the host frequencybandwidth.

18. A method according to clause 17, wherein the first virtual carrierincludes one or more other control channels for providing other controlinformation, and the controller is configured in combination with thereceiver unit to receive other control information from the othercontrol channels.

19. A mobile communications network comprising

one or more infrastructure equipment configured to form a wirelessaccess interface for transmitting data to or receiving data fromcommunications devices, the wireless access interface providing aplurality of communications resource elements across a host frequencybandwidth, and including within the host frequency bandwidth, a firstsection of communications resource elements within a first frequencybandwidth for allocation preferably to reduced capability devices toreceive signals representing the data transmitted by the transmitterunit within the first bandwidth forming a first virtual carrier, thereduced capability devices each having a receiver bandwidth which isgreater than or equal to the first frequency bandwidth but less than thehost frequency bandwidth, and the infrastructure equipment is configured

to receive from a communications device a relative capability of thecommunications device to receive signals representing the data via thewireless access interface, the relative capability comprising at leastan indication of a relative bandwidth of the communications device toreceive the signals within the host frequency range greater than orequal to the first bandwidth, and

to allocate communications resources elements which includecommunications resource elements which are outside the first frequencybandwidth, but within the bandwidth of the communications device, inresponse to the indication of the relative capability of thecommunications device.

20. A mobile communications network according to clause 19, wherein theinfrastructure equipment is configured

to receive signals from and/or transmit signals to communicationsdevices in accordance with a one of a predetermined set of classes ofcommunications devices, each class defining a different frequencybandwidth within which the communications device can receive signalsfrom the infrastructure equipment, and

to transmit a resource allocation message to the communications devicewhich allocates shared communications resource elements to thecommunications device within a bandwidth corresponding to one of apredetermined number of classes of the communications device.

21. A mobile communications network according to clause 20, wherein theinfrastructure equipment is configured

to receive from one of the communications devices the class of thecommunications device from one of the predetermined classes, each classdefining a different frequency bandwidth within which the communicationsdevice can receive signals from the wireless access interface.

22. A mobile communications system comprising a mobile communicationsnetwork and a communications device,

the mobile communications network comprising one or more infrastructureequipment configured to form a wireless access interface fortransmitting data to or receiving data from communications devices, thewireless access interface providing a plurality of communicationsresource elements across a host frequency bandwidth, and including,within the host frequency bandwidth, a first section of communicationsresource elements within a first frequency bandwidth for allocationpreferably to reduced capability devices to receive signals representingthe data transmitted by the transmitter unit within the first bandwidthforming a first virtual carrier, the reduced capability devices eachhaving a receiver bandwidth which is greater than or equal to the firstfrequency bandwidth but less than the host frequency bandwidth, and thecommunications device is configured

to transmit to the mobile communications network a relative capabilityof the communications device to receive data via the wireless accessinterface, the relative capability comprising at least an indication ofa relative bandwidth of the receiver unit within the host frequencyrange greater than or equal to the first bandwidth, and

the infrastructure equipment is configured

to receive from the communications device the relative capability of thecommunications device and in response to allocate communicationsresource elements which are outside the first frequency bandwidth to thecommunications device, but within the bandwidth of the communicationsdevice, in response to the indication of the relative capability of thecommunications device.

The invention claimed is:
 1. A communications device that communicateswith a mobile communications network, the mobile communications networkincluding one or more network elements providing a wireless accessinterface for the communications device, the communications devicecomprising: a transmitter configured to transmit unlink data to themobile communications network via the wireless access interface; areceiver configured to receive downlink data from the mobilecommunications network via the wireless access interface, wherein thewireless access interface provides a plurality of communicationsresource elements across a host frequency bandwidth, and the pluralityof communications resource elements includes, within the host frequencybandwidth, a first section of communications resource elements forming afirst virtual carrier containing a first frequency bandwidth, the firstvirtual carrier for allocation to reduced capability devices andincluding a physical downlink control channel (PDCCH) portion common toa plurality of reduced capability devices and a first physical downlinkshared channel (PDSCH) portion allocated exclusively for use by anothercommunications device, and the reduced capability devices each having areceiver bandwidth which is greater than the first frequency bandwidthbut less than the host frequency bandwidth; and processing circuitryconfigured to control the transmitter transmit, to the mobilecommunications network, a relative capability of the receiver to receivethe downlink data via the wireless access interface, the relativecapability including an indication of a relative bandwidth of thereceiver to receive signals within the host frequency bandwidth, therelative bandwidth being greater than the first frequency bandwidth andsmaller than the host frequency bandwidth, wherein the receiverreceives, from the mobile communications network in response to theindication an allocation of communications resource elements, theallocation of communications resource elements by the PDCCH of the firstvirtual carrier including communications resource elements which areoutside the first frequency bandwidth and that form a second virtualcarrier including a second PDSCH portion allocated exclusively for useby the communications device, but within the relative bandwidth of thereceiver, and which encompass the first frequency bandwidth, the firstvirtual carrier abuts the second virtual carrier in bandwidth, and thesecond PDSCH portion of the second virtual carrier is larger in timewithin a subframe than the first PDSCH portion of the first virtualcarrier.
 2. The communications device as claimed in claim 1, wherein themobile communications network allocates the communications resourceelements outside the first frequency bandwidth based on a capacity ofthe first virtual carrier and a demand by the reduced capabilitydevices.
 3. The communications device as claimed in claim 1, wherein thetransmitter is configured to transmit uplink signals and the receiver isconfigured to receive downlink signals according to a bandwidthcorresponding to one of a predetermined set of classes of communicationsdevices, and the receiver is configured to receive, from the mobilecommunications network, a resource allocation message which allocatescommunications resource elements within a bandwidth corresponding to thepredetermined class of the communications device.
 4. The communicationsdevice as claimed in claim 3, wherein the processing circuitry isconfigured to control the transmitter to communicate to the mobilecommunications network the class of the device from one of apredetermined set of classes, each class defining a different frequencybandwidth within which the communications device receives signals fromthe wireless access interface, which is greater than or equal to thefirst frequency bandwidth.
 5. The communications device as claimed inclaim 4, wherein the processing circuitry is configured to control thetransmitter and the receiver to attach to the mobile communicationsnetwork, control the receiver to receive, in response to attaching tothe mobile communications network, a request to communicate anindication of the class to which the communications device belongs, andcontrol the transmitter to transmit, in response to the received requestfor the class of the communications device, the indication of the classof the communications device.
 6. The communications device as claimed inclaim 1, wherein the receiver is configured to receive signalinginformation that indicates a location of the second virtual carrierwithin a second section of communications resource elements within theplurality of communications resource elements, the second virtualcarrier for allocation to the reduced capability devices, the secondvirtual carrier containing a second virtual carrier bandwidth that iswithin the host frequency bandwidth, and in accordance with a capabilityof the communications device, the communications device is configured toreceive signals allocating communications resource elements from thesecond virtual carrier and the first virtual carrier.
 7. Thecommunications device as claimed in claim 6, wherein the receiver isconfigured to receive the resource allocation message on the PDCCH inthe first virtual carrier, the processing circuitry is configured todetermine, from the resource allocation message on the PDCCH message,that the communications device has been allocated communicationsresource elements within one of the first virtual carrier and the secondvirtual carrier, and the receiver is configured to receive signals fromthe mobile communications network from the allocated communicationsresource elements of the one of the first virtual carrier and the secondvirtual carrier.
 8. The communications device as claimed in claim 1,wherein the first frequency bandwidth of the first virtual carrier islocated substantially at a center of the host frequency bandwidth. 9.The communications device as claimed in claim 8, wherein the firstvirtual carrier includes one or more other control channels forproviding other control information, and the receiver is configured toreceive other control information from the other control channels.
 10. Amethod of communicating with a mobile communications network by acommunications device, the mobile communications network including oneor more network elements providing a wireless access interface for thecommunications device, the method comprising: transmitting, by atransmitter of the communications device, uplink data to the mobilecommunications network via the wireless access interface: receiving, bya receiver of the communications device, downlink data from the mobilecommunications network via the wireless access interface, wherein thewireless access interface provides a plurality of communicationsresource elements across a host frequency bandwidth, and the pluralityof communications resource elements includes, within the host frequencybandwidth, a first section of communications resource elements forming afirst virtual carrier containing a first frequency bandwidth, the firstvirtual carrier for allocation to reduced capability devices andincluding a physical downlink control channel (PDCCH) portion common toa plurality of reduced capability devices and a first physical downlinkshared channel (PDSCH) portion allocated exclusively for use by anothercommunications device, and the reduced capability devices each having areceiver bandwidth which is greater than the first frequency bandwidthbut less than the host frequency bandwidth; transmitting, by thetransmitter to the mobile communications network, a relative capabilityof the receiver to receive the downlink data via the wireless accessinterface, the relative capability including an indication of a relativebandwidth of the communications device to receive signals within thehost frequency bandwidth, the relative bandwidth being greater than thefirst frequency bandwidth and smaller than the host frequency bandwidth;and receiving, by the receiver from the mobile communications networkand in response to the indication, an allocation of communicationsresources, the allocation of communications resource elements by thePDCCH of the first virtual carrier including communications resourceelements which are outside the first frequency bandwidth and that form asecond virtual carrier including a second PDSCH portion allocatedexclusively for use by the communications device, but within therelative bandwidth of the receiver, and which encompass the firstfrequency bandwidth, wherein the first virtual carrier abuts the secondvirtual carrier in bandwidth, and the second PDSCH portion of the secondvirtual carrier is larger in time within a subframe than the first PDSCHportion of the first virtual carrier.
 11. The method as claimed in claim10, wherein the receiving the communications resources outside the firstfrequency bandwidth are allocated based on a capacity of the firstvirtual carrier and a demand by the reduced capability devices.
 12. Themethod as claimed in claim 10, wherein the transmitter transmits theuplink signals and the receiver receives the downlink signals inaccordance with a bandwidth corresponding to one of a predetermined setof classes of communications devices, and receiving the method furthercomprises a resource allocation message from the mobile communicationsnetwork which allocates shared communications resources within abandwidth corresponding to the predetermined class of the communicationsdevice.
 13. The method as claimed in claim 12, wherein the transmittingto the mobile communications network the relative capability includestransmitting, to the mobile communications network, a class of thedevice from one of a predetermined set of classes, each class defining adifferent frequency bandwidth within which the communications devicereceives signals from the wireless access interface, each class having aminimum bandwidth of the virtual carrier.
 14. The method as claimed inclaim 13, wherein the transmitting the class of the device from one of apredetermined set of classes includes attaching to the mobilecommunications network, receiving, in response to attaching to thecommunications network, a request to communicate an indication of theclass to which the communications device belongs, and transmitting, inresponse to the received request for the class of the communicationsdevice, the indication of the class of the communications device. 15.The method as claimed in claim 10, further comprising: receivingsignaling information that indicates a location of the second virtualcarrier within a second section of communications resource elementswithin the plurality of communications resource elements, wherein thesecond virtual carrier being for allocation to reduced capabilitydevices, and the second virtual carrier containing a second frequencybandwidth that is within the host frequency bandwidth; and receiving, inaccordance with a capability of the communications device, signalsrepresenting data at the communications device from the second virtualcarrier.
 16. The method as claimed in claim 15, wherein the methodfurther comprises: receiving, at the communications device, a resourceallocation message on the PDCCH in the first virtual carrier;determining, from the resource allocation message in the PDCCH that thecommunications device has been allocated communications resources withinone of the first virtual carrier and the second virtual carrier; andreceiving signals from the mobile communications network from theallocated communications resources elements of the one of the firstvirtual carrier and the second virtual carrier.
 17. The method asclaimed in claim 10, wherein the first frequency bandwidth of the firstvirtual carrier is located substantially at a center of the hostfrequency bandwidth.
 18. The method as claimed in claim 17, wherein thefirst virtual carrier includes one or more other control channels forproviding other control information, and the method further comprisesreceiving other control information from the other control channels. 19.A reduced capability communication device that communicates with amobile communications network, the mobile communications networkincluding one or more network elements providing a wireless accessinterface for the communications device, the reduced capabilitycommunication device comprising: processing circuitry configured totransmit uplink data to the mobile communications network via thewireless access interface; receive downlink data from the mobilecommunications network via the wireless access interface, wherein thewireless access interface provides a plurality of communicationsresource elements across a host frequency bandwidth, and the pluralityof communications resource elements includes, within the host frequencybandwidth, a first section of communications resource elements forming afirst virtual carrier containing a first frequency bandwidth, the firstvirtual carrier for allocation to the reduced capability communicationdevice and including a physical downlink control channel (PDCCH) portioncommon to a plurality of reduced capability devices and a first physicaldownlink shared channel (PDSCH) portion allocated exclusively for use byanother communications device, and the reduced capability communicationdevice having a relative bandwidth that is greater than the firstfrequency bandwidth but within the host frequency bandwidth; transmit,to the mobile communications network, a relative capability of thereduced capability communication device to receive the downlink data viathe wireless access interface, the relative capability including anindication of the relative bandwidth; and receive, from the mobilecommunications network in response to the indication, an allocation ofcommunications resource elements, the allocation of communicationsresource elements by the PDCCH of the first virtual carrier includingcommunications resource elements which are outside the first frequencybandwidth and that form a second virtual carrier including a secondPDSCH portion allocated exclusively for use by the communicationsdevice, but within the relative bandwidth and which encompass the firstfrequency bandwidth, wherein the first virtual carrier abuts the secondvirtual carrier in bandwidth, and the second PDSCH portion of the secondvirtual carrier is larger in time within a subframe than the first PDSCHportion of the first virtual carrier.